Curiously, (Formula presented) desorption from Si(100)-2×1 follows approximately first-order kinetics rather than the expected second-order kinetics, arousing interest about the mechanism involved in the desorption process. We investigate the energetics and rate constants of three proposed mechanisms for (Formula presented) desorption from Si(100)-2×1, namely, the prepairing mechanism, the isomerization mechanism, and the isolated dihydride mechanism, using complete active space self-consistent-field and multireference single- and double-excitation configuration-interaction calculations. We find the desorption barrier for the isolated dihydride mechanism to be 2.49 eV, the only barrier in excellent agreement with the experimentally determined barrier (∼2.5 eV). The isolated dihydride mechanism also provides the only calculated desorption rate constant close to experimental values. Finally, we show that this mechanism is able to explain the experimentally observed apparent violation of detailed balance of (Formula presented) adsorption/desorption on Si(100), as well as other experimentally observed dynamics.
|Original language||English (US)|
|Number of pages||15|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Jan 1 1996|
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics